Updated models with AMD graphics options expected in early 2017.
Apple Updates Logic Pro and MainStage, Adds 64-Bit Compatibility
Adding 64-bit support to Logic 9.1 and MainStage 2.1 effectively removes the memory limit imposed on 32-bit applications running under Mac OS X. When running the apps in 64-bit mode, users can take advantage of any memory left after allocating the system, plug-ins and other apps.As addressed in an Apple FAQ support document, users of 32-bit plug-ins will be able to use Logic Pro and MainStage in 64-bit mode, with Apple's new 32-bit Audio Unit Bridge serving to provide compatibility with those plug-ins.
The report also notes that there are several features in Logic Pro and MainStage that are not yet functional in 64-bit mode, so users should make note of those limitations before deciding which mode to use. Full details of the changes in Logic Pro 9.1 and MainStage 2.1 are available in release notes posted on Apple's site.
Apple released its updated Logic Studio suite in July and had issued a couple of minor updates before today's major point release.